In recent years, various types of treatments and diagnoses have been performed in the medical field using an elongated and hollow tubular-shaped medical instrument called a catheter. Examples of such treatment methods include directly administering an agent into an affected area by using the elongatedness of the catheter, opening a narrowed section in the body lumen by using a catheter in which a balloon expanded by pressure is attached to a distal end thereof, scraping and opening the affected area by using a catheter in which a cutter is attached to a distal section of the catheter, and closing arterial aneurysm, bleeding, or feeding vessel sites with a filling material using the catheter. Other examples include embedding and placing a tubular-shaped stent which has a mesh-shaped side surface into the body lumen using the catheter so as to maintain an open state of the narrowed section in the body lumen, and suctioning excess liquid for a body in the body.
In general, in a case where the treatment, diagnosis, or the like is performed using the catheter, a introducer sheath is introduced into a puncture site formed in an arm or a leg and the catheter or the like is percutaneously inserted into a lesion area such as a blood vessel via a lumen of the introducer sheath.
Usually, a valve body that prevents blood reflux while allowing the device such as the catheter or a dilator to be inserted is disposed in a hub of the introducer sheath, which has a structure such that the device is inserted via the valve body from an opening section disposed on a proximal side of the hub. An example is disclosed in Japanese Application Publication No. 8-131552.
Also, in the introducer sheath according to U.S. Pat. No. 6,322,541, a deformable valve body in which a through-hole that has a slit is formed is bent so as to adjust hemostasis by and insertibility of the device.
However, in the introducer sheath disclosed in Japanese Application Publication No. 8-131552, the opening section into which the device such as the catheter is narrow, and an outer circumference of the opening section is formed to be a flat surface, and thus it is difficult to insert the device.
Also, in the introducer sheath according to U.S. Pat. No. 6,322,541, a hub surface and a cap surface sandwiching the valve body are bent, and thus the valve body is likely to be moved along the bending of the hub and the cap when the device is inserted. In addition, the introducer sheath according to U.S. Pat. No. 6,322,541 may be changed the hemostasis and the insertibility of the device by the degree of fusion of the cap.